Cellular telephones, laptop computers, and a wide variety of similar mobile devices use radio frequency (RF) radiation to connect to and/or communicate with other users, entities, and networks using the public switched telephone network, the Internet, private networks, public safety networks, and other transmission paths and networks. Studies on the effects of RF radiation to the human body have, for some time, been controversial and not, arguably, conclusive. Much difficulty has attended the building and use of newer and ever-larger and more comprehensive arrays of antennas such as cellular telephone “cell” antennas, and the production and use of ever-smarter and often more powerful and complex cellular telephones and other mobile devices.
As a result, mobile communication devices such as cellular telephones have recently evolved not only for the transmission of voice as was the original intent, but also for the transmission of text, data, and multimedia. Thus, a cellular telephone is a misnomer and such devices should more aptly be referred to as a wireless personal digital assistant (PDA) or a mobile computer. Due, at least in part, to this technological evolution, the use of mobile communication devices has increased exponentially.
Nevertheless, mobile communication devices continue to present problems. Many issues relate to the effects on children, and it is thought that, for all users, the most vulnerable body parts might be the brain, eyes, and groin. For example, one problem is the radiated electromagnetic fields that might affect a user's brain when hand-held devices are held in close proximity to the user's head. In order to address this problem, at least in part, the Federal Communication Commission (FCC) has set radio frequency (RF) exposure guidelines that recommend a maximum permissible exposure level. Specifically, the FCC has established a specific absorption rate (SAR) of 1.6 milliwatts per kilogram (W/kg) or less. The term SAR as used herein is the amount of energy of an electromagnetic wave transmitted by a wireless transceiver, such as a mobile telephone, during a phone call and absorbed by a specific part (especially, a head) of a human body for six minutes, and is measured as an average over a 10-gram cube of a human tissue.
Despite communication companies developing devices that are in compliance with the FCC guidelines, there is a growing concern that health problems (such as brain cancer) might be attributed to use of the aforementioned mobile communication devices.
To address concerns over the amount of energy of electromagnetic waves transmitted by wireless transceivers, various studies have been performed to analyze the electromagnetic interaction of handset antennas and a user. These studies have resulted in suggestions for an improved design of the handset antenna. In addition, proposals exist for attempting to solve the absorption by a user's body, and its health consequences, such as brain cancer. See U.S. Pat. No. 7,031,657 to Tehrani and U.S. Patent Application Publication No. 2010/0159916 to Ezer at al. that both use an intermediate transceiver between a mobile device and a main antenna of a cellular telephone network that operates at a different frequency/intensity than the mobile device.
Shielding devices are also used in an attempt to reduce radiation, and many patents have been issued that include an antenna shield. See U.S. Pat. No. 6,075,977. However, due to proximity of the antenna to the user's body, the radiation problem still exists. In addition, the shield might adversely affect reception of the antenna, which could lead to an increase in absorption of energy because the cellular telephone attempts to compensate for the reduced reception. Thus, shielding by itself is not necessarily an optimal solution for radiation exposure.
Accordingly, alternative solutions have been proposed in an attempt to reduce radiation exposure. As is recognized in the art, the farther away the user's body is from the antenna, the less power absorption by the user's body. Thus, many prior art solutions propose to increase the distance between an antenna and the user. This approach is somewhat helpful to reduce the radiation absorbed by the user by increasing the distance between the user and the antenna. This is often achieved using a short wire, which limits the positioning of the handset with a maximum distance of arm's length to the brain. Alternatively, a wireless headset might be used, which lets the user roam around the office with the headset using short-range communication such as Bluetooth technology. However, most of these systems are not practical for a user walking in the street, for example.
However, none of the above mentioned references improve the performance of the mobile electronic devices that use long-range radio frequency (RF) communication, while reducing the SAR level at the head of the user of the mobile device.
Thus, there clearly exists a need for an efficient, yet compact and simple device capable of retransmitting RF communication signals received from mobile electronic devices that improves the performance of the mobile devices, and also reduces the SAR of such mobile devices at the head of the user.